It is known that a preferable technique in cooking involves the use of burning coal and to cook or barbecue food by holding this above the burning coals and to some extent having inflammable by-products resulting from the cooking flare by being inflamed when hitting the burning coals and this technique for grilling, especially meat, is well known and indeed conventional.
This technique however suffers from several problems among which is the difficulty that it can be difficult to control the degree of flaming and the outside of the food can be overcooked or burned or charred because of excess fat resulting from heating of the food dropping into the burning coals.
Conversely if there is insufficient fat, the food can have substantially all of the fat removed and this can therefore be considered as dried out and of course one of the skills of cooking with this type of technique is to keep the food both moist, correctly cooked through, and not excessively charred on the outside.
A further difficulty is the problem experienced by those who attempt to provide significant quantities of food cooked to these standards typically commercial caterers, who wish to offer the advantage considered to be offered by cooking over hot coals rather than other forms of heating and suffer the further difficulty then of being able to provide significant quantities of food within a short period of time correctly cooked and yet do not wish to have excessive quantities of equipment that they must take from location to location if it is a portable hire concept nor in terms of costs associated with providing of coals do they also want large fire beds if this can be avoided nor do they want, if this can be avoided, to have to individually tend any cooking of food on a very often basis.
Perhaps a typical previous installation and method of cooking can be considered in which a fire is lit and kept burning within a half cylinder and positioned significantly above both the fire and the sides of the container holding the fire is the food to be cooked which may typically be the carcass of an animal such as a sheep or a pig and this is cooked very slowly and to assist in reducing charring the pig is rotated generally about its own longitudinal axis and preferably some moistening fluid is added in the form of basting from time to time.
The period of time normally associated with such method of cooking is very long indeed and some ten to twelve hours would be perhaps typical, it is conventional that the outside of the food is charred often to the stage of being inedible, and there is an associated risk because of the low temperatures involved and the long time involved, that some of the food especially that susceptible to bacterial contamination may by reason of such bacterial growth promoted by the conditions and not overcome because of the low temperatures, become dangerous to the health of those who may afterwards eat the food. The trauma and economic cost of such problems will be well known to those who might have experienced this difficulty.